The present invention generally relates to an undermount support, to support and install sinks. More specifically, the invention relates to an undermount support that is primarily used to support and install all types and shapes of kitchen and bathroom undermount sinks, and may also be used to support countertops, kitchen countertop cooktops, and bathroom vessel sinks, such as those typically found in new residential construction.
Undermount sinks are primarily manufactured from stainless steel, copper, quartz, composite, fireclay or enameled cast iron, and are generally available in single, double and triple bowl configurations. Almost all undermount sinks have a continuous top rim flange that is designed to carry the full weight of a loaded sink.
Larger single and double-bowl undermount kitchen sinks may fit into European designed box style cabinets (frameless) that are approximately 36-inches long (Ikea). The heaviest double bowl sinks are made of enameled cast iron and can weigh up to 144 lbs. The manufacturer of these sinks recommends that the support structure be capable of supporting 300 pounds, and that the sink not be attached directly to the underside of the countertop.
Triple-bowl undermount kitchen sinks are generally manufactured from stainless steel or copper, are approximately 40-inches to 48-inches long, and require substantial support when fully loaded with water, dishes, pots and cutlery, etc. Again, it is not recommended to attach heavy triple-bowl sinks directly to the underside of a countertop, which often includes a large sink cut out and many faucet holes, as the countertop is at its weakest at this location. Accordingly, triple-bowl enameled cast iron sinks are usually drop-in (top mount) units due to their weight.
Various methods of mounting undermount sinks are presently being used. One popular method is to construct a permanent wooden frame (generally mounted inside the cabinet) on which the sink's rim flange sits. The countertop (quartz, granite, marble and concrete, etc) is then installed over the sink and cabinet using a silicon sealant between the sink's rim flange and the countertop. The silicon will become contaminated with bacteria and mold. The only way to completely remove all of the old silicon and properly clean the adjoining surfaces is by dismantling the wooden support structure or by lifting the countertop. Generally, it will be difficult to try to dig out and replace the contaminated silicon that can be seen without disturbing the wooden frame, sink or countertop. This is not considered a proper repair and the life of the fresh silicon will be reduced.
U.S. Pat. No. 5,538,208 to Sather discloses an undermount sink support that sits (rests) on the top edges (can be secured by screws) of the vertical elements of the cabinet that support the countertop. Vertical adjustment screws make contact with the sink's rim flange and are used to support and align the sink. Turning out the adjustment screws would allow the sink to be lowered slightly (after cutting through the silicon bead located between the sink's top rim flange and countertop and disconnecting the drain's plumbing), allowing the old silicon to be replaced. However, this type of design gives very little space (limited by screw thread length and longitudinal rail clearance) for proper removal of the silicon and proper cleaning of the adjoining surfaces. The sink cannot be completely removed (lowered) as the side supports sit on top of the cabinet's vertical elements and are usually held in place by screws. If the screws were to be left out, the support structure could be removed. Reinstallation, however, would be tricky due to the lack of working space, as the sink would have to be held in place as the supports are relocated. Another problem with this type of support structure is that it only intermittently supports two sides of the sink's rim flange using adjustment screws (rim is continuous around four sides). This allows the support structure, the sink's rim flange and the silicon joint to flex as weight is applied and released (normal filling and emptying of the sink with water, dishes, pots and cutlery, etc), and over time causes the silicon to delaminate, which enhances the promotion of bacteria and mold.
U.S. Pat. No. 5,743,501 to Rapp discloses an improved support (mounting) structure but still only intermittently supports (vertical adjustment screws) two sides of the sink's rim flange and again, to a lesser degree, allows the support structure, the sink's rim flange and silicon joint to flex as weight is applied and released. With this design, the adjustment screws are mounted in the slotted support rails and make contact with the sink's rim flange, and are again used to support and align the sink. This design could allow the sink to be lowered slightly (after cutting through the silicon bead located between the sink's top rim flange and countertop and disconnecting the drain's plumbing), allowing the old silicon to be replaced. Again, this type of design provides very little space for proper removal of silicon and proper cleaning of adjoining surfaces. The sink cannot be removed (lowered), as the side support bracket's fingers are located in the top nut receptacle channel of the rails. The side support brackets also sit on top and overhang the cabinet's vertical elements and are usually held in place by screws. In this configuration, the support structure and sink must be installed before the countertop is installed. Also the cabinet's vertical side's top surface must be recessed to allow the side supports to sit flush with the top surface that makes contact with the bottom side of the countertop. The alternative is to place the rail's open underside on top of the fingers, which would allow the rails to be removed. Mounting the rails on top of the fingers is not as secure as using the nut receptacle channel. Reinstallation would be tricky due to the lack of working space, as the sink would have to be held in place as the supports are relocated.
Another problem with support structures that use adjusting screws that directly make contact with the sink's rim flange (metal to metal) is the transmission of sound through the support structure to the cabinet's box structure. The cabinet can in some cases amplify the sound generated by the sink. Plastic pads are sometimes fitted to the adjusting screws to prevent metal to metal contact.
U.S. Pat. No. 6,986,174 to Brown discloses another type of mounting structure using seaming compound and perforated mounting plates that are bonded to the underside of the countertop. This can be a problem when using European cabinets, as insufficient space is available to locate the mounting plates and brackets. Intermittently mounting the plates and brackets around the sink's rim flange will cause the flange and silicon joint to flex as weight is applied and released. Also, bonding failures have occurred with fully loaded sinks, causing the sink to drop.
Still other methods are available to attach the sink to the underside of the countertop. One of the more popular of these methods is to drill blind holes in the underside of the countertop and fit epoxy threaded inserts into the holes. The holes can be drilled on all four sides where the sink's flange will sit (generally up to eight holes, if space permits). Any time a hole is drilled into the underside of a countertop, stress risers are setup, which can lead to cracking. Studs are then installed into the threaded inserts, and brackets are attached to the studs using threaded nuts or wing nuts. The brackets make contact with the sink's rim flange and the underside of the countertop. When the nuts are tightened, the sink is pulled into contact with the underside of the countertop. Over-tightening of the nuts can cause the inserts to pull out and sometimes cause the countertop to crack. The main advantage of this mounting structure over the adjustment screw and rail type is that the sink can easily be lowered to replace the silicon joint, and sound transmission to the cabinet is very low.
Various other support structures have been used to support or attach an undermount sink to the underside of a countertop. One example uses four brackets that are hammered into the cabinet's vertical support's top and side surfaces (two per side) before the countertop is fitted. The brackets have adjusting screws that make contact with the sink's rim flange. No longitudinal rails are used in this design and the sink's rim flange is only intermittently supported at the two ends by the four adjusting screws (sink's rim flange is continuous around four sides). This allows the sink's rim flange and the silicon joint to flex as the sink's rim flange is not supported along the two main longitudinal runs, which would cause excessive distortion and delamination of the rim flange silicon joint. The main advantage of this mounting structure over the adjustment screw and rail type is that the sink can be lowered to replace the silicon joint. However, sound transmission to the cabinet is high compared to the present invention.
A low cost design that does not use adjusting screws, or the sink's rim flange for support, is the universal sink harness that uses wire loops attached to the cabinet's vertical sides by clips (two per side for a double bowl sink). Each clip is attached to the cabinet's side by two screws. The wire is attached to one clip, is then passed under the sink's bowl and attached (wrapped around) to a draw bolt, and then returned and attached to the other clip on the same side to form a wire loop. The second wire is attached to one clip on the opposite side of the cabinet's vertical side and is passed under the sink's bowl, attached to a draw bracket and then returned and attached to the other clip on the same side (forms a second wire loop). The wire loops cradle the underside of the sink's bowl(s) with the draw bolt and draw bracket, joining the two side wire loops together. Silicon is applied to the sink's rim flange, and the draw bolt (attached to the draw bracket) is then turned to tighten the two wire loops, pulling the sink into contact with the underside of the countertop. Alternatively, silicon is applied to the sink's rim flange and the sink is lifted into position and aligned with the countertop cut out. One or two clamps are then passed through the sink's drain hole(s) (drain(s) not fitted) which grab the underside of the sink while the top jaw(s) of the clamp(s) grab the topside of one or two pieces of lumber placed across and overlapping the countertop's cut out. The clamp(s) is/are tightened, holding the sink in place. The draw bolt is then tightened and the clamp(s) is/are removed.
The main advantages of this mounting harness are: the sink can easily be lowered to replace the silicon joint; the entire portion of the sink's rim flange is in contact with the underside of the countertop; weight can be transferred from the countertop to the cabinet's sides; low manufacturing cost; it is simple to install; it will fit most types and size of sinks; and it is rated to carry a maximum of 250 lbs. However, the problem with this design is that the tensioned wires tend to pull the cabinet's sides in towards the sink, distorting the cabinet's sides, especially if the sides are manufactured from particle board.
Another cause for concern with the use of the mounting harness is how much support it achieves at the center of long double and triple-bowl undermount sinks. Most double and triple-bowl undermount sinks are manufactured with individual bowls that are joined at the top by the rim flange. The bottom of the bowls on high quality sinks are generally tied together using flat metal stripping which stiffens the sink and reduces flexing (longitudinal bending). Bowls that are not tied together will require greater support to reduce flexing to an acceptable level. As noted above, the harness' wire loops located at both ends of the underside of the sink's bowls are attached to the side clips and are not completely parallel (vertical) to the cabinet's vertical sides, causing weight from the sink and countertop to pull the cabinet's sides in towards the sink. The wires attached to the clips provide most of the vertical force that holds the sink to the underside of the countertop when the wires are put under tension. The wires under the sink's bowls are parallel to the sink's top rim flange. This parallel tension tends to pull the sink's outer bowls in towards the center of the sink, which causes the sink's rim flange to deflect upwards in its middle section, especially if the bowls are not tied together. When the sink is loaded, the middle section will tend to drop as the horizontal wires provide very little, if any, vertical support, causing the silicon joint to flex and delaminate. The present invention solves this problem by supporting 100% of the sink's rim flange on all four sides.
Another cause for concern when using the mounting harness comes when tightening the draw bolt. The sink can be raised too far and lift and damage the countertop, and/or the harness assembly. Another potential problem with the harness is the transmission of sound through the tensioned harness wires connected to the cabinet's box structure by the four clips. The cabinet can, in some cases, amplify the sound generated by the sink.
Accordingly, it is an object of the present invention to provide additional support to a countertop, especially when using box-style cabinets.
It is another object of the invention, with dishwasher installations, where the span between the cabinet's vertical walls is approximately 24-inches, to support the countertop located over the dishwasher as the dishwasher cannot make contact with the countertop.
It is still another object to provide a structural support for a countertop and a drop-in electric or gas cooktop insert that requires a large cut-out in the countertop of generally 30-inches to 44-inches in length.
It is a further object, with bathroom vessel sink installations, where the span between the cabinet's vertical walls can be up to 36-inches or more, to support such a countertop and vessel sink, particularly when used with the latest European 1-cm or 2-cm thick countertops that require extra support when mounting heavy natural stone vessel sinks.